The junction box was available from a UK supplier for a reasonable price, with free next-day delivery. I immediately started printing the various inserts to hold everything in place.

When the box arrived the next day, I first screwed in the bottom insert, then attached the particle sensor, and then screwed in the top insert. I also had to attach the temperature and humidity sensor and take care of all the wiring. Finally I added the ESP8266 board on top.

Once everything was installed, I turned it on. I could connect to the ESP8266 over the network, but for some reason the particle sensor recorded 0 $\mu\textrm{g/m}^3$. I couldn't hear the fan of the sensor turn on, and then realised that one of my screws was too long and was preventing the fan from turning. After loosening the screw a bit, everything was working really well.

The previous owners of our house had a satellite dish, but as we are not using it, I decided to remove the dish and re-use the hole in the wall to install a USB cable to power the air quality monitor. I tried pushing a micro-USB cable through the existing hole, but even a cable with a small micro-USB connector would not fit.

I found a 1.8 metre long micro-USB cable that was stripped and tinned on the other side, to make it easier to push through the hole in the wall and then solder to an old USB cable on the inside. This turned out to be the trickiest part of the build, as soldering very thin USB cables takes a lot of patience. I also used some heat shrink to keep everything nice and tidy after soldering.